linux-kernel - Re: [PATCH] fdt: Extend warnings on error paths

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Message-ID: <20250423202326.GA1025526-robh@kernel.org>
Date: Wed, 23 Apr 2025 15:23:26 -0500
From: Rob Herring <robh@...nel.org>
To: Bartosz Szczepanek <bsz@...zon.de>
Cc: Saravana Kannan <saravanak@...gle.com>, nh-open-source@...zon.com,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fdt: Extend warnings on error paths

On Wed, Apr 23, 2025 at 09:10:17AM +0000, Bartosz Szczepanek wrote:
> Print out adress and size if elfcorehdr is overlapped. Be more verbose
> about what went wrong in case early_init_dt_verify fails. Other than
> improving logging, no functional change is intended in this commit.
> 
> Signed-off-by: Bartosz Szczepanek <bsz@...zon.de>
> ---
>  drivers/of/fdt.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index aedd0e2dcd89..c9b5e056b713 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -469,21 +469,22 @@ static u32 of_fdt_crc32;
>   * described in the device tree. This region contains all the
>   * information about primary kernel's core image and is used by a dump
>   * capture kernel to access the system memory on primary kernel.
>   */
>  static void __init fdt_reserve_elfcorehdr(void)
>  {
>  	if (!IS_ENABLED(CONFIG_CRASH_DUMP) || !elfcorehdr_size)
>  		return;
>  
>  	if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
> -		pr_warn("elfcorehdr is overlapped\n");
> +		pr_warn("elfcorehdr is overlapped (addr=0x%llx, size=%llu)\n",
> +			elfcorehdr_addr, elfcorehdr_size);
>  		return;
>  	}
>  
>  	memblock_reserve(elfcorehdr_addr, elfcorehdr_size);
>  
>  	pr_info("Reserving %llu KiB of memory at 0x%llx for elfcorehdr\n",
>  		elfcorehdr_size >> 10, elfcorehdr_addr);
>  }
>  
>  /**
> @@ -1128,26 +1129,33 @@ void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
>  	memblock_add(base, size);
>  }
>  
>  static void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
>  {
>  	return memblock_alloc_or_panic(size, align);
>  }
>  
>  bool __init early_init_dt_verify(void *dt_virt, phys_addr_t dt_phys)
>  {
> -	if (!dt_virt)
> +	int rc;
> +
> +	if (!dt_virt) {
> +		pr_warn("FDT wasn't correctly mapped");

You need a '\n' here. Technically, it doesn't, but IIRC it won't get 
flushed out immediately without. Of course, this runs too early to see 
the message typically.

It's possible some arch has a fallback if this function fails and 
doesn't want the warning, but we can apply and see.

>  		return false;
> +	}
>  
>  	/* check device tree validity */
> -	if (fdt_check_header(dt_virt))
> +	rc = fdt_check_header(dt_virt);
> +	if (rc) {
> +		pr_warn("FDT header is invalid: status=%d", rc);
>  		return false;
> +	}
>  
>  	/* Setup flat device-tree pointer */
>  	initial_boot_params = dt_virt;
>  	initial_boot_params_pa = dt_phys;
>  	of_fdt_crc32 = crc32_be(~0, initial_boot_params,
>  				fdt_totalsize(initial_boot_params));
>  
>  	/* Initialize {size,address}-cells info */
>  	early_init_dt_scan_root();

Normal context is 3 lines. Please send patches that way.

Rob